Question

When 90 is added to a number it equals 30 less than 3 times the number.

Answer 1

The number is 60.

Explanation:

Let x = unknown number.

Now we translate the sentence into an equation, one piece at a time.

When 90 is added to a number it equals 30 less than 3 times the number.

x + 90

When 90 is added to a number it equals 30 less than 3 times the number.

x + 90 = 3x - 30

We now solve the equation for x.

Subtract 3x from both sides.

-2x + 90 = -30

Subtract 90 from both sides.

-2x = -120

Divide both sides by -2.

x = 60

The number is 60.

Check:

When 90 is added to a number it equals 30 less than 3 times the number.

Add 90 to 60:

90 + 60 = 150

We get 150.

When 90 is added to a number it equals 30 less than 3 times the number.

Now multiply 60 by 3 and subtract 30.

3(60) - 30 = 180 - 30 = 150

We also get 150.

That means our answer of 60 is correct.

Answer: 60

Answer 2

90+x=30-3[x]

Explanation:

collect like terms

x+3x=30-90

4x=-260

divide both sides by 4

x=-60/4

x=-4*3*5/4

x=-[3*5/1]

x=-[3*5]

x=-15